Papers by Author: Yun Zhang

Abstract: In cold rolling process, asymmetric shape defects are still a common problem to strip quality. For the mills with inverse symmetry roll shifting system, different roll wear and thermal contour of top roll system and bottom roll system could cause asymmetric shape defects during shifting operation. In this paper, three dimension finite element simulation models of inverse shifting roll system were established to calculate the parameters and to analyze the effects. Based on the idea in the mill engineering that mill style option depended on the product grade, shifting weakness was evaluated and the opinion of limit shifting was suggested. To improve control effect to asymmetric shape defects in cold rolling, shape control system with asymmetric shape control ability is developed, including asymmetric edge drop control at upstream stands and asymmetric flatness control at last stand. The further improvement of asymmetric shape control theory and practice is the key way to reach the higher precision of shape quality in cold strip mills.

Abstract: In order to analyze the effect of entry strip thickness, entry strip crown and intermediate roll shifting on strip profile and rolling force distribution, a three dimension finite element model of rolls-strip in UCM mill was established and employed. The results showed that the increases of entry strip thickness and entry strip crown would lead to the increase of exit strip crown and edge drop under the same total rolling force; the strip crown and edge drop would be decreased if the intermediate roll shifting δi was decreased. Moreover, the rolling force distribution also was analyzed in details by changing the entry strip thickness, the entry strip crown and the intermediate roll shifting.

Abstract: Au/SiO2 nano-composite multilayer thin films with different thickness were prepared on a quartz substrate by magnetron plasma sputtering. The microstructure, morphology and optical properties of the films were investigated by using TEM and optical absorption spectra. [Au/SiO2]×5 and [Au/SiO2] × 11 multilayer thin films have well-defined interface. The thickness of the multilayer was 60nm and 130 nm for the thin films with 5 and 11 layers, respectively. The optical absorption peaks due to the surface plasma resonance appeared at a wavelength of 560 nm for the both [Au/SiO2]×5 and [Au/SiO2]×11 thin films. The intensity of the absorption peak increased with increasing numbers of deposition layers. The optical absorption spectra of Au/SiO2 multilayer thin films are well agreement with the theoretical optical absorption spectra calculated from rewritten Maxwell–Garnett effective medium theory.